In order to carry out the industrial cooking of ham, cooking it in a cooking chamber of relatively large volume is known. The hams are wrapped respectively in cooking bags which should be disposed in cells forming a cooking mould of a stackable unit.
When this first stackable unit is full, it serves as a support for other stackable units which in that case should be filled and then stacked successively one upon another in order to form a stack which is next transferred into a cooking chamber. In certain cases when, for example, the cooking is carried out in a cooking chamber containing a heat-conducting fluid, the stacking is performed inside the cooking chamber by means of a manipulator robot.
In order to allow the shaping of the ham during its cooking, each cell comprises on its bottom a pressing means intended to press a ham disposed in a cell of another stackable unit of a lower rank. This pressing means consists for example of a plate mounted fixed on the bottom of a cell. The last stackable unit stacked is generally empty and serves only as a pressing means for the stackable unit of the lower rank.
In view of the large mass of a stack of stackable units, it is important to position a stackable unit accurately with respect to another stackable unit of a lower rank so that the pressing means of said stackable unit can press properly, that is to say repetitively, the hams of the stackable unit of a lower rank.
Furthermore, in order to obtain gains in productivity, the manipulator robots responsible for performing the transfer of the stackable units, and in particular their stacking, work at high speed and therefore cause swaying of the stackable units which still persists at the time of their stacking.
Although equipped with positioning means, the known stackable units do not allow sufficient positioning accuracy to be obtained between them during their stacking.